1. Field of the Invention
The present invention relates to routers and Session Initiation Protocol (SIP) servers, and more specifically, to a router incorporating a technology for controlling the Quality of Service (QoS) of packets in an Internet Protocol (IP) network and a SIP server specifying the QoS of the router through the IP network.
2. Description of the Related Art
As broadband access to an IP network has become widespread in recent years, applications requiring real-time capabilities such as telephony and live video distribution on the IP network have been increasing. The IP network is originally configured by a best-effort network and may not be ready for communication with near-real-time characteristics.
Technologies for assuring the QoS of a network have become important, and a variety of such technologies have been standardized. One of those technologies currently used is a traffic-oriented control technology referred to as Differentiated Services (Diff-Serv).
In a Diff-Serv network made up of boundary nodes and interior nodes, different levels of Quality of Service are provided by relatively varying transfer capabilities, for instance, in accordance with a Differentiated Services Code Point (DSCP) value specified in each packet. The DSCP value of an Internet Protocol Version 4 (IPv4) packet is specified in the Type of Service (ToS) field of the IPv4 header. The DSCP value of an Internet Protocol Version 6 (IPv6) packet is specified in the Traffic class field of the IPv6 header.
The DSCP value can be specified initially by a user terminal of an end user who can recognize a service. The DSCP value in each header can also be rewritten by a boundary node router when a certain condition is met. General conditions specified in the boundary node router include an IP address, a TCP port number, a UDP port number, and others.
More specifically, packets to be given higher priority are selected and marked, and the marked packets are allowed to pass the network ahead of the other packets. The manner of prioritization is managed by each router.
SIP has come into widespread use as a protocol of real-time communication such as telephony on an IP network. SIP is a signaling protocol for establishing a session necessary for communication and for changing and disconnecting the session. The establishment of a SIP session includes negotiations on a service using the session, the number of the port to be used, a communication protocol, and others. Accordingly, SIP can be easily combined with a different existing protocol and has a high extensibility.
One technology for use in a Diff-Serv network or a SIP network as described above is disclosed in patent document 1 indicated below, for instance. The technology blocks voice communication which is not permitted by a SIP server, by providing a firewall function which can be controlled from a call processing server (SIP server) for access servers, boundary node routers, and other access apparatuses provided in access points where a carrier network is connected, on a router basis. Patent document 1 also discloses a technology of allowing an access apparatus provided in an access point to specify the QoS of a packet identified by a combination of a source IP address, a destination IP address, a source port number, a destination port number, and others, as instructed by the SIP server. Another technology disclosed in the document allows the SIP server to store information indicating which user terminal is served by which access apparatus, together with the Internet telephone user information stored as the user information.
A switch disclosed in patent document 2 indicated below, for instance, has a function to convert a non-SIP signal output by a non-SIP terminal, such as a PBX signal, into an SIP message, and vice versa. This function enables communication between a non-SIP telephone and a SIP terminal.
With the technologies disclosed in patent documents 3 and 4 indicated below, for instance, if a caller or a calling terminal sends a SIP protocol message including additional information describing the intention of the caller, the server identifies a called party optimum for the intention and establishes a SIP session accordingly.
Patent Document 3 describes that a caller-side end point generates a SIP INVITE request which includes the standard routing information in its header portion and the additional information on the intention of the caller in its body portion. For instance, the header may contain the address of a consumer electric manufacturer, and the additional information given in the body may contain keywords associated with the caller such as “washing machine,” “service,” and “model ABC.” In accordance with the information, the call is directed to a salesperson skilled in answering questions about services of washing machine model ABC.
Patent Document 4 discloses a method in which a proxy server judges the most accurate address to which a call is directed, using the routing information specified in the INVITE message and detected voice cookie information. If a call is made to a customer sales division and if detected voice cookie information includes the name of the salesperson who talked with the caller most recently, the proxy server automatically directs the call to the salesperson, not to any other salesperson available.
A method disclosed in patent document 5, for instance, enables mutual authentication between a SIP client and a SIP proxy, by incorporating a Kerberos security system in the message flow of the SIP signaling operation. When the SIP proxy receives a request message from the SIP client, the SIP proxy sends a challenge message indicating that Kerberos authentication is necessary. In response to the message, the SIP client sends a second request message including authentication data containing a Kerberos server ticket to the proxy. Then, the proxy authenticates a client user.
[Patent Document 1] Japanese Unexamined Patent Application Publication No. 2003-229893
[Patent Document 2] Japanese Unexamined Patent Application Publication No. 2002-118594
[Patent Document 3] Japanese Unexamined Patent Application Publication No. 2002-335267
[Patent Document 4] Japanese Unexamined Patent Application Publication No. 2003-22223
[Patent Document 5] Japanese Unexamined Patent Application Publication No. 2003-108527
Suppose that a SIP server and a boundary node router jointly implement the Diff-Serv function, using the conventional technologies. The SIP server stores beforehand information indicating which boundary node router is connected to the Internet telephone of the corresponding user, or information correlating the address of the user terminal to the address of the boundary node router serving the user. Based on the information, the SIP server specifies the QoS requested by the user in the boundary node router serving the user terminal.
If the boundary node router serving the user terminal is changed because of the movement of the user terminal to another site, the addition of a new boundary node router, a change in the network configuration, and other reasons, the QoS of the user cannot be assured. If the user uses a user terminal which is not associated with a boundary node router, the same problem occurs.
Conventionally, each time the relationship between a user terminal and a boundary node router serving the terminal is changed by moving the user terminal or the like, the maintenance person updates the corresponding management information of the SIP server. If a large amount of information must be changed, the update operation will take a long time, and user QoS control cannot be specified for a certain period. An error in the updated information may hinder correct QoS control.